This project continues the investigation of the dextran-synthesising systems of several cariogenic strains of Streptococcus mutants. The component dextransucrases of the synthetic systems will be purified to electrophoretic homogeneity and characterised, and the kinetics and mechanism of their catalytic reactions will be studied with respect to the substrates, acceptors and products involved in the reactions. The role of cell surface dextransucrases and of divalent cations in the specific agglutination of Streptococcus mutants cells by dextrans will also be studied.